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[oletrucks] rearends for 454, trannys, gear ratios

To: Old Trucks List <oletrucks@autox.team.net>
Subject: [oletrucks] rearends for 454, trannys, gear ratios
From: J Forbes <jforbes@primenet.com>
Date: Wed, 04 Apr 2001 21:30:17 -0700
An oletruck with a 454...what more could you want?  
:)

The 10 bolt car rearends are probably adequate, IF
you get the right one (8.5" ring gear) AND you make
sure it's in good condition.  The axles wear out
where the bearings ride;  the pinion gear may crack
at the base of the teeth (requires removing the
bearings to see it); the spider gears/side gears get
tired after lots of miles; some of the factory posi
units are not very strong....

These same problems occur on the car and truck 12
bolt rearends, and the F*rd 9" rears have some
different problems, such as weak posi units
(although the detroit locker is very strong, but has
some handling quirks), and with any rearend, if it's
used, it's probably in need of a complete
overhaul--definitely a complete (take it apart)
inspection at the minimum.

I like to run a stock (with mild shift kit) rebuilt
TH400, with a switch pitch torque converter, and
highway gears, behind big blocks.  Gears around 2.75
to 3.0 work great with a mild cam and about 2000 rpm
stall speed, or with a bigger cam you can run 3.50
gears and 2500 stall and really go quick.  The 8.5"
ten bolt (used in most all 70-81 Camaros) is about
the minimum strength rearend to use, the 12 bolt
truck rearend from the 60s-70s works well if you
want to keep 6 lugs, but they got wider in 1970, so
measure carefully.  The F*rd 9" will be fine if you
get a good one and make it fit...this can get
expensive, though.  For example, the 9" in my 55
Belair was bought used, I paid $800 for the Summers
Brothers housing and axles and brakes, and then
bought a Detroit Locker (they cost over $400 in the
catalogs) and new bearings, and I had some good used
gears.  You can easily spend $2000 at Currie or
similar places for a 9" built to your specs, with
nothing exotic in it.

The 700R4 is ok if you want to spend a lot of $$$
getting one built to last behind a big block, but it
seems to me to be false economy.  With a big block
and steep gears, you're gonna smoke the tires, so
you might as well put mild gears in it, and just run
a 3 speed automatic.  You can put a mild stall
converter in a TH400 and get most of the benefit of
steeper gears.

Jim F
59s in AZ
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959

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